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Luke Miller, Matthew Longo, Ayse Saygin; Vision during tool use is both necessary and sufficient for recalibration of tactile perception of body size. Journal of Vision 2015;15(12):362. doi: https://doi.org/10.1167/15.12.362.
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© ARVO (1962-2015); The Authors (2016-present)
The brain combines information across sensory modalities to construct finely calibrated multisensory models of the body. The parameters of these models are largely dependent upon online sensory feedback, particularly visual. For example, visually magnifying a body part recalibrates somatosensory perception on it. Tool use has also been shown to recalibrate tactile perception on the tool-using limb. Here, we show that vision during tool use is both necessary and sufficient for recalibrating tactile perception. In a series of experiments, we assessed tactile distance judgments on the hand and arm before and after tool use. Responses were fit with psychometric functions using a maximum likelihood estimation technique; a difference between the pre- and post-PSE indexed tool-induced perceptual recalibration. Following the use of a hand-shaped tool, we found significant recalibration in tactile processing on the hand (Experiment 1). No recalibration was found when subjects were blindfolded during tool use, demonstrating a necessary role for visual feedback (Experiment 2). We next investigated whether vision is sufficient for recalibration. We used a mirror visual illusion to decouple visual and somatosensory feedback during tool use. Participants viewed a reflection of their right arm while keeping their left arm stationary behind a mirror. After participants used the tool with their right arm, we found significant perceptual recalibration on the left forearm, even though this limb remained completely stationary (Experiment 3). This effect was abolished when subjects performed the reaching task with their right arm only (Experiment 4), held the tool stationary (Experiment 5), or used the tool without the mirror box (Experiment 6). Taken together, these studies demonstrate that vision during tool use is both necessary and sufficient for recalibrating multisensory models of body size. The importance of overt tool movement in the illusion further suggests an important role for visual biological motion mechanisms in embodiment.
Meeting abstract presented at VSS 2015
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